From this story on CNN.com:
In the 1990s, a researcher named Kris Pister dreamed up a wild future in which people would sprinkle the Earth with countless tiny sensors, no larger than grains of rice. These "smart dust" particles, as he called them, would monitor everything, acting like electronic nerve endings for the planet. Fitted with computing power, sensing equipment, wireless radios and long battery life, the smart dust would make observations and relay mountains of real-time data about people, cities and the natural environment. Now, a version of Pister's smart dust fantasy is starting to become reality. "It's exciting. It's been a long time coming," said Pister, a computing professor at the University of California, Berkeley. "I coined the phrase 14 years ago. So smart dust has taken a while, but it's finally here."